Superior mesenteric artery (SMA) syndrome is a gastro-vascular disorder in which the third and final portion of the duodenum is compressed between the abdominal aorta (AA) and the overlying superior mesenteric artery. This rare, potentially life-threatening syndrome is typically caused by an angle of 6–25° between the AA and the SMA, in comparison to the normal range of 38–56°, due to a lack of retroperitoneal and visceral fat (mesenteric fat). In addition, the aortomesenteric distance is 2–8 millimeters, as opposed to the typical 10–20.[1] However, a narrow SMA angle alone is not enough to make a diagnosis, because patients with a low BMI, most notably children, have been known to have a narrow SMA angle with no symptoms of SMA syndrome.[2]
SMA syndrome is also known as Wilkie's syndrome, cast syndrome, mesenteric root syndrome, chronic duodenal ileus and intermittent arterio-mesenteric occlusion.[3] It is distinct from nutcracker syndrome, which is the entrapment of the left renal vein between the AA and the SMA, although it is possible to be diagnosed with both conditions.[4]
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